1. Field of the Invention
This invention relates to a pulley apparatus and, more particularly, to a novel hydraulically actuated pulley apparatus adapted to be attached to a member of a structural body, such as an automobile, for pulling the member with respect to the body for moving, straightening or performing any other desired work on the member or the body itself during the repair thereof.
2. Description of the Prior Art
Heretofore, it has been the conventional practice to use handtools, such as angle irons and crowbars in repairing automobile body parts. The advantage in using such tools is the easy maneuverability of the tools and the ready access that these tools permit in reaching these parts. Although these tools have been successfully employed in the past, several problems and difficulties have been encountered which severely limit their utilization.
On occasions when a large amount of force is needed in pulling or straightening body members, the pulling force generated by these leverage tools is usually insufficient to move these members. Furthermore, in order to gain any leverage, the body members sometimes act as a fulcrum for the tools. This oftentimes results in marring the appearance of or even damaging the members, which, of course, is undesirable. What is often required in aligning or straightening a body member is a steady continuous force acting to move the member only a few inches, but to an exact position. A common fault of the handtools is overpull, where a short burst of force carries the member past its intended aligned position.
It is recognized therefore, that in many situations some mechanical apparatus must be used in providing the means for working on automotive body members. A common means used is a pulley arrangement such as a block and tackle apparatus. In such a device, the mechanical advantage developed by the pulleys provides the pulling force that is required. However, such devices are usually not maneuverable enough to permit widespread usage and often require overhead beams, cranes, and other expensive and unwieldy apparatus. As a general rule, the angle of the pulling force on a body member varies numerously, depending on the position of the member and the manner in which it must be straightened or aligned. Since the block and tackle must be anchored from the same angle as the direction of the pulling force, such a device is often impractical to employ because such various anchoring positions are not readily available or, in fact, possible.